This invention relates generally to mine ventilation, more particularly to mine overcast and mine undercast structures (generally, mine air crossings), i.e., a structure for the intersection of two passageways or airways in a mine wherein air is flowing in each passageway or airway for ventilation, the installation thereof in the mine as completed functioning to by-pass air flowing in one airway over the other airway at the intersection to avoid interference of one flow with the other, and the method of installation.
Reference is made to the co-assigned U.S. Pat. No. 5,412,916 of William R. Kennedy and John M. Kennedy dated May 9, 1995 entitled “Structure Having Quick-Connect Components”, U.S. Pat. No. 5,466,187 of John M. Kennedy and William R. Kennedy dated Nov. 14, 1995 entitled “Mine Ventilation Structure”, U.S. Pat. No. 6,256,946 B1 of William R. Kennedy and John M. Kennedy dated Jul. 10, 2001 and U.S. Pat. No. 6,264,549 B1 of William R. Kennedy and John M. Kennedy dated Jul. 24, 2001 for background on mine overcasts and undercasts (including their function and prior overcast structure). Reference is also made to the co-assigned U.S. patent application Ser. No. 10/038,356 of William R. Kennedy and John M. Kennedy filed Jan. 4, 2002 entitled “Mine Ventilation Structure and Deck Panels Therefor”. All these patents and applications are incorporated herein by reference. And reference is further made to the book titled “Practical Mine Ventilation” by William R. Kennedy, Second Edition published 1999 by Intertec Publishing Corporation of Chicago, Ill.